PaeA (YtfL) protects from cadaverine and putrescine stress in Salmonella Typhimurium and E. coli

Yumi Iwadate, Rouhallah Ramezanifard, Yekaterina A Golubeva, Luke A Fenlon, James M Slauch

Research output: Contribution to journalArticlepeer-review

Abstract

Salmonella and E. coli synthesize, import, and export cadaverine, putrescine, and spermidine to maintain physiological levels and provide pH homeostasis. Both low and high intracellular levels of polyamines confer pleiotropic phenotypes or lethality. Here, we demonstrate that the previously uncharacterized inner membrane protein PaeA (YtfL) is required for reducing cytoplasmic cadaverine and putrescine concentrations. We identified paeA as a gene involved in stationary phase survival when cells were initially grown in acidic medium, in which they produce cadaverine. The paeA mutant is also sensitive to putrescine, but not to spermidine or spermine. Sensitivity to external cadaverine in stationary phase is only observed at pH > 8, suggesting that the polyamines need to be deprotonated to passively diffuse into the cell cytoplasm. In the absence of PaeA, intracellular polyamine levels increase and the cells lose viability. Degradation or modification of the polyamines is not relevant. Ectopic expression of the known cadaverine exporter, CadB, in stationary phase partially suppresses the paeA phenotype, and overexpression of PaeA in exponential phase partially complements a cadB mutant grown in acidic medium. These data support the hypothesis that PaeA is a cadaverine/putrescine exporter, reducing potentially toxic levels under certain stress conditions.

Original languageEnglish (US)
JournalMolecular Microbiology
Early online dateJan 22 2021
DOIs
StateE-pub ahead of print - Jan 22 2021

Keywords

  • cadaverine
  • polyamines
  • putrescine
  • Salmonella
  • stationary phase

ASJC Scopus subject areas

  • Molecular Biology
  • Microbiology

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